it's important to
后跟做什么=do sth.,表示去做什么很重要
it's important for
后跟什么=sth.,表示对什么很重要
例：
it's important to ask this question
问这个问题很重要
it's important for you
这对你很重要
最后,以上词组可以合起来用
it's important for sb.to do sth.
例：
it's important for you to ask this question
问这个问题对你很重要